In a related art, there is known a color laser printer of a so-to-speak tandem type in which process cartridges in correspondence with toners of respective colors of yellow, magenta, cyan, black are arranged to align in a horizontal direction. Each process cartridge is provided with a photosensitive drum for carrying a toner image in each color to be placed onto a sheet, a developing apparatus including the toner in each color to be held on a surface of each photosensitive drum.
According to the color laser printer of the tandem type, for example, a belt supported by a plurality of rollers is arranged to be brought into contact with the photosensitive drum provided at each process cartridge from a lower side thereof. The sheet is carried to successively pass between the belt and each photosensitive drum by being guided on the belt. While carrying the sheet, the toner image carried by each photosensitive drum is transferred onto the sheet. Thereby, a multi-color image is formed on the sheet at a speed substantially the same as a speed of forming a monochromatic image.
Each photosensitive drum is irradiated with laser beam from an exposing apparatus based on image data, by selectively exposing a surface of the photosensitive drum which is previously charged, an electrostatic latent image in correspondence with the image data is formed, the toner is supplied to the surface of each photosensitive drum in correspondence with the electrostatic latent image, thereby, the toner image is carried by each photosensitive drum. There is an image forming apparatus including a plurality of exposing apparatus in correspondence with respective photosensitive drums for exposing corresponding photosensitive drums by the respective exposing apparatus (for example, refer to JP-A-2003-266865).
According to the image forming apparatus disclosed in JP-A-2003-266865, the plurality of exposing apparatus in correspondence with the respective photosensitive drums are supported by a single base slidably attached to a main body frame of the color laser printer. The base is movable between a state inside of the main body frame and a state of being moved from the main body frame in a horizontal direction while the base is still supported by the main body frame.
When an operation of replacement of the exposing apparatus or an operation of checking a light source or an optical part provided to the respective exposing apparatus is carried out, by moving the base from the main body frame, all of the exposing apparatus are brought into a state outside the main body frame. The respective exposing apparatus may be detached from the base.